The Flow Cytometry Shared Resource provides technical expertise, trained personnel, and technical services in flow cytometry to meet the needs of Cancer Center members. The specific services of the Flow Cytometry Shared Resource include 1) quantitative measurement of fluorescent receptors to assess the distribution of specific molecules within cell populations 2) sorting to isolate purified populations of cells based on detection of specific probes such as antibodies or green fluorescent protein. This Shared resource provides analyses using expensive equipment within individual investigators could not afford. The well-trained staff can provide timely analyses. Both the efficiency of the facility and the contribution of CCSG funds reduce investigator costs. Use of this shared resource has increased from 120 hours in 1996 to 892 hours in 1998.